Purpose: Periodontitis is a common chronic disease globally. It is a major cause of tooth loss among adults, and recently has been suggested as a possible risk factorfor some systemic diseases such as cardiovascular disease. In Saudi Arabia, research on periodontitis prevalence, as well as its relation to systemic diseases, is lacking. The objectives of this study were: (1) to determine the prevalence of periodontitis among a sample of Saudi Dental School patients population; and (2) to examine the association between periodontitis and systemic diseases in the selected sample., Materials and Methods: Retrospective evaluations of 282 randomly selected dental records were conducted. Age, gender, nationality and medical history were abstracted from these records. Number of remaining teeth and number of teeth with more than 20% of bone loss were determined from panoramic radiographs. Descriptive statistics, t-test, chi-square and regression models were used for data analyses., Results: About 68% of the sample had radiographic alveolar bone loss; of these, 28% had a localised and 40% had a generalised form. Prevalence of systemic diseases was generally higher among individuals with the generalised form. About 21% and 13% of those with generalised periodontitis reported history of diabetes and hypertension respectively, whereas only about 2% of those with localised periodontitis reported history of these diseases., Conclusion: The findings of the present study showed a high prevalence of periodontitis in the selected sample. There is an urgent need for further studies with larger sample size to confirm these findings and to implement an effective measure to reduce periodontitis prevalence in Saudi Arabia.